Formaldehyde detection using Sn doped ZnO thin film

Abstract

This work presents an approach for formaldehyde detection using Sn doped ZnO thin film. The concentration of Sn dopant varies at 0.5at%, 1.0at% and 1.5at%. XRD results show that the thin film possessed a crystallite structure with the highest peak at 002. The crystallite size of undoped, 0.5at%, 1.0at% and 1.5at% Sn doped ZnO thin film are 10.09 nm, 33.36 nm, 8.736 nm and 9.31 nm, respectively. Surface roughness obtained from AFM was 16.9 nm, 10.19 nm, 5.48 nm and 8.57 nm for undoped 0.5at%, 1.0at% and 1.5at% Sn doped ZnO thin film, respectively. The optimal sensitivity is acquired when 1.0at% Sn doped ZnO thin film is used for the detection of 3.4 ppb formaldehyde, where the sensing performance is 92%; while the sensing performance of undoped thin film is only 50%. The response time for undoped and 1.0at% Sn doped ZnO thin film is 10-8 s and 4-10 s, while the recovery time is 38-207 s and 15-34 s, respectively. The 1.0at% Sn doped ZnO thin film also demonstrates a good response in formaldehyde sensing, which was measured for nine consecutive days, where the sensing performance was over 90%.